Device and method for closing containers having a closure

ABSTRACT

The invention relates to a device and to a method for closing containers ( 3 ) having a closure ( 1 ), particularly a bottle closing machine. Said machine has at least one closing head ( 4 ) displaced in a direction toward a container opening ( 2 ) along a displacement path (H) for applying the closure ( 1 ). To this end, a prescribed external force (F A ) is applied to the closing head ( 4 ). According to the invention, the closing head ( 4 ) comprises an internal force supporting element ( 6, 7 ) supporting the externally applied force (F A ).

The invention relates to a device for closing containers with a closure, in particular a bottle closing machine, said device including at least one closing head, which, for applying the closure, is displaced in a predominantly axial manner in the direction of a container opening along a displacement path and for this purpose is acted upon by a predetermined force from outside.

During this operation, the closing head can be moved towards the container. Obviously a reverse method of operation is also conceivable where the respective container is raised to the closing head. A simultaneous movement of the container and the closing head is also conceivable. The force from outside can be exerted directly onto the closing head via a control element that moves said closing head. In so far as the container is moved, for example, from below towards the closing head and is placed against said closing head by way of its opening, the force from outside results from a control element, which raises the container and as a result produces a corresponding counterforce at the fixed closing head.

A device of the afore-described design is proposed in DE 10 2006 035 279 A1. This case looks at a closing machine for closing bottles or similar containers with closures. Here different closing positions each with a closing tool are formed on a rotating rotor for securing the closure. Each closing position has associated therewith at least two closing tools that are held on a tool carrier. By moving the tool carrier, the closing tools can be moved at least between an operating position and a standby position. In the operating position, the closing tool brings about the securing of the closures to the respective container. The closing tools are closing cones that are rotatably mounted in the tool carrier.

Comparable devices for closing containers or rather bottle closing machines are known in practice. In the case of all these devices, the closing head is acted upon by a force from outside when applying or attaching the closure to or on the container opening. Said force is exerted, for example, by the tool carrier according to the DE 10 2006 035 279 A1 onto the closing tool or the closing head.

Such an impingement of force is necessary in order, on the one hand, to attach the closure in a fault-free manner on the container opening, for example by means of screw-connection. On the other hand, during the closing operation the pressure often rises inside the container such that the screw-connecting operation in the case in example has to be completed with increasing force impingement. This means that the pressure exerted onto the closure and consequently also onto the bottle, with the closing head remaining in the identical position, has still to be sufficiently high in the end position of the closure, that means at the end of the displacement path, in order to be able to close the container in a fault-free manner.

On account of said requirement profile, the problem that arises in practice is that the pressure onto the screw-type closure or onto the container, with the closure head remaining in the identical position, is on the whole unnecessarily high in particular at the start or beginning of the displacement path, in order to be still sufficient for the fault-free closure at the end of the displacement path or in the end position. As the closing head or the container is acted upon by a force from outside, and in particular disposable bottles to be closed made of PET are not very stable when in the open state (for example when filled with carbonated beverages), this application of force creates the risk that the bottle becomes canted or in the worst case deformed, in any case the desired closing operation cannot be performed. In the extreme case, this even results in the entire bottle closing machine coming to a standstill. This is where the invention fits in.

The technical problem underlying the invention is to develop a device of this type further in such a manner that the closure can be attached in a fault-free manner and any downtimes that have occurred in this connection no longer do so. In addition, a suitable method for closing such containers is to be provided.

This technical problem is solved within the framework of the invention by a generic device for closing containers with a closure, characterized in that the closing head has an internal force-supporting element, which supports the force applied from outside by means of an inner force that is generated by means of the force-supporting element.

Within the framework of the invention, the closure for closing the container (and as a consequence also all the containers) is therefore acted upon during this operation by a compound force. First of all, a force from outside, for example exerted by a control element working directly on the closing head, acts as before on the closing head. However, it is also possible for the closing head to be connected to a tool carrier, as is described in DE 10 2006 035 279 A1 and said tool carrier then experiences with the control element an effect of force from outside or a force from outside is exerted onto the respective container and as a result onto the closing head. In the majority of cases the last-named method of operation is selected because normally several containers conveyed on a circular path are each provided at the same time with an associated closing head and experience closure one after another.

In addition to said force from outside, which acts on the closing head and/or the container and displaces the closing head axially in the direction of the container opening along the displacement path or raises the container and places it against the closing head, according to the invention there is added another inner or internal force. Said inner or internal force is exerted by the internal force-supporting element. To this end, the force-supporting element is located in the interior of the closing head such that the relevant inner force is generated directly in the interior of the closing head and is exerted on said closing head.

In this context it has proved especially favourable for the closing head to be designed as a whole in two parts. In the majority of cases there is an accommodating head for the closure at one end and a base at the other end. The displacement path is then set in such a manner that the accommodating cup is displaced axially in relation to the base.

In this case, the described inner and the external force, as a rule, work on at least one spring element in the interior of the closing head for the compression of said spring element. The spring element is supported at the one end on the accommodating cup for the closure and at the other end on the base. The accommodating cup dips into a guide cylinder of the base thus defining the displacement path. In this case, the internal force-supporting element is located parallel to the said spring element. In the majority of cases the spring element surrounds the force-supporting element because the spring element is advantageously a helical spring with spiral-like turns.

It has proved of value for the force-supporting element to be realized as a magnetic element that is made up of two magnets, in particular permanent magnets. In this case, the two magnets are located in the majority of cases lying opposite each other with different poles. In addition, the invention recommends that the closing head as a whole be developed in a rotationally symmetrical manner in comparison with an axis of rotation. In the majority of cases, the closing head is rotated about said axis of rotation in order to apply the closure onto the container opening and to close said container opening by means of the (screw-type) closure.

The inner force and the external force act substantially in the same direction on the spring element, which is located in the interior of the closing head. As already described, the spring element is clamped at the one end between the accommodating cup for the closure and at the other end between the base. As soon as a force from outside is exerted onto the closing head, this results in the spring being compressed and the accommodating cup dipping increasingly into the guide cylinder.

The identical operation occurs when the internal force-supporting element or the magnetic element becomes effective at this position. For by the force-supporting element being connected at one end to the accommodating cup and at the other end to the base, the internal force-supporting element, just as the internal spring element, is connected at one end to the accommodating cup and at the other end to the base and consequently can contribute directly and in a supplementary manner to the external force for the compression of the spring element. This applies more than ever in an advantageous manner because the force-supporting element and the spring element have substantially identical lengths and overlap each other.

In this case, the design overall is such that the force-supporting element or the magnetic element made of the two magnets corresponds to a certain spacing between the magnets at the beginning of the displacement path, the spacing between said two magnets reducing to zero or almost zero at the end of the displacement path. This means that it is not only the accommodating head dipping into the guide cylinder of the base that defines the displacement path, but said displacement path is also fixed and restricted at the same time by the magnets of the force-supporting element that is realized as a magnetic element, said two magnets initially being spaced apart and then moving towards each other.

On account of said arrangement and design, the force-supporting element or magnetic element also develops an inner force that mounts along the displacement path in the direction of the container opening. For said mounting inner force results from the increasing, exponentially in the majority of cases, and mounting attractive force between the two magnets as the space between them becomes smaller. This also shows clearly that both the inner force and the external force act on the spring element substantially in the same direction for the compression of said spring element. In reality, both the external force and the inner force act on the spring element with an aligned force component, which extends substantially in the longitudinal direction of the spring element or of the helical spring. Generally speaking, the longitudinal direction of the helical spring or of its axis of rotation coincides all in all with the axis of rotation of the closing head. This ensures that the closure accommodated in the accommodating cup, and as a result also the container, experiences, as a whole, the desired axial force impingement during the closing operation.

As a result, a device for closing containers with a closure and an associated method are described, by means of which the closure can be applied to the container opening in a fault-free manner. For the external force acting from outside on the closing head to compress the spring element in its interior is reduced according to the invention compared to the prior art. The internal force-supporting element located in the closing head is responsible for this, said internal force-supporting element acting in the identical direction as the external force and also compressing the spring element. This means that, as a result, the external force working on the closing head is reduced not only at the beginning of the displacement path but also along the entire displacement path compared to previous methods of operation, even an additional decrease in the external force towards the end of the displacement path being observed. That is in stark contrast to the object of the prior art, which operates with an increasing external force along the displacement path and in particular at the end of the displacement path so as to be able to compensate for the mounting counterforces shortly before the complete closure of the container opening.

These mounting counterforces can be explained, as a rule, on account of the fact that carbonated beverages, in particular, generate a not inconsiderable pressure in the interior of a bottle produced, for example, from PET, which is expressly desired. For it is only through this increased pressure that the stability necessary for the subsequent conveying operation of such (disposable) PET bottles is made available.

As according to the invention the closing head is acted upon and can be acted upon with an external force that is clearly reduced compared to the prior art, the bottle canting when the closure is applied, damage to said bottle etc. are reduced to a minimum or can be completely ruled out. This can be traced back primarily to the fact that an external force engaging the closing head in a non-precise manner always corresponds to a more or less large torque at the container opening, which is the cause of the described canting leading to damage to the bottle.

By this external force being significantly reduced now according to the invention, the engaging torques are also reduced to a minimum. Rathermore, by applying the force-supporting element or the magnetic element internally, it is not just the external force that is reduced, but the inner force applied by the internal force-supporting element also acts almost exclusively axially which means that such cantings or instabilities no longer occur.

In this case the inner force, built-up by the force-supporting element and mounting in the majority of cases exponentially as the space between the magnets gets smaller, is responsible for the fact that the external force applied onto the closing head is at least partially compensated for along the displacement path such that the closing head, all in all with unchanged force and as a result unchanged pressure, is responsible for attaching the closure during the closing operation. This means that that actual closing operation is completed with similar force impingement as before, however with external force that is clearly reduced compared to this along the entire displacement path.

The invention is explained below by way of a drawing representing just one exemplary embodiment, in which, in detail:

FIG. 1 shows a schematic representation of the device according to the invention, reduced to the essential components and

FIG. 2 shows a force-path curve as is completed according to the invention with the closing head.

The Figures show a device for closing containers in each case with a closure 1, said device within the framework of the case in example being a bottle closing machine, which is similar in basic design to that described in detail in DE 10 2006 035 279 A1. By means of the device shown or of the bottle closing machine, the closure 1, which is not restricted to being developed as a screw-type closure, is applied onto a container opening 2 of a container 3.

In a non-restricting manner, the container 3 is a disposable PET bottle that accommodates a carbonated beverage in its interior or which has been filled in a station connected upstream before the closure 1 is applied onto the container 3. The individual containers 3 or bottles are guided regularly along a circular path, each container 3 having associated therewith its own closing head 4. All the closing heads 4 may be connected to a rotatingly circulating tool carrier, which is, however, not shown in detail. At all events, the closure 1 can be applied to the container opening 2 by means of the closing head 4 by the closing head 4 being displaced along a displacement path H in the direction of the container opening 2. Obviously as an alternative or as an addition, the container 3 can also be raised in the direction of the closing head 4. The displacement path H corresponds to a stroke H of approximately 10 to 15 mm in the case in example, which is completed by the closing head 4 when applying the closure 1.

It is recognized that the closing head 4 is designed substantially in two parts and in detail includes an accommodating head 4 a for accommodating the closure 1 and a base 4 b with guide cylinder 4 c. The accommodating head 4 a can be moved relative to the base 4 b or the guide cylinder 4 c. In the case of this operation, the accommodating head 4 a dips into the guide cylinder 4 c of the base 4 b and in this manner defines the displacement path or stroke H.

A spring element 5 is connected between the accommodating head 4 a at the one end and the base 4 b at the other end, said spring element in the exemplary embodiment being a helical spring with helical turns, which extend in the shape of a spiral in comparison with an axis of rotation A. Compared to said axis of rotation A, the entire closing head 4 is rotationally symmetrical and can also be rotated about said axis of rotation A, as indicated by a double arrow in FIG. 1. By rotating the closing head 4 about the axis of rotation A, the closure or screw-type closure 1 is screw-connected onto the container opening 2 of the container or of the bottle 3 in the case in example.

Just as the spring element or the helical spring 5, a force-supporting element 6, 7, to be described in more detail below, is supported at one end on the accommodating cup 4 a and at the other end on the base 4 b. The force-supporting element 6, 7 is located parallel to the spring element 5, in an axial manner in comparison with the common axis of rotation A. In this case, the design is made such that the spring element 5 surrounds the force-supporting element 6, 7. The force-supporting element 6, 7 and the spring element 5 overlap each other.

It is recognized that the internal force supporting element 6, 7 in the case in example is composed of two magnets 6, 7, and is realized, as a result, as a magnetic element 6, 7. In this case, the two magnets 6, 7 are located opposite each other with different poles N, S, as is made clear directly in FIG. 1.

An external force F_(A) engaging from outside onto the closing head 4 in the axial direction or along the axis of rotation A is supported by means of the force-supporting element or the magnetic element 6, 7. For the internal force-supporting element 6, 7, that-is-to-say located in the interior of the closing head 4, also exerts an inner or internal force F_(I) onto the closing head 4. In this case, the two forces, that-is-to-say the external force F_(A) and the inner force F_(I) operate in the same direction and work together on the spring element 5 to compress said spring element. The spring element 5 itself acts upon the accommodating cup 4 a in the direction of the container opening 2. In addition, the inner force F_(I) mounts along the displacement path H in the direction of the container opening 2, in an almost exponential manner, as is clear by way of the representation in FIG. 2 and is explained again in more detail below.

The method of operation is as follows. Beginning in the position represented in FIG. 1, the prestressed spring element or the helical spring 5 is responsible for providing that the accommodating cup 4 a supporting the closure 1 is at its maximum distance from the base 4 b. For to this end, the accommodating cup 4 a is provided with a circumferential ring 9, which abuts against an associated ring abutment 9 of the guide cylinder 4 c of the base 4 b. In this position the closing head 4 is placed above the container or the bottle 3, obviously aligned axially in comparison with the axis of rotation A. The container or the bottle 3 is already filled with a liquid or a beverage.

The closing head 4 is then impinged upon with the force from outside or the external force F_(A) in the axial direction A by means of a control element (not shown) or by means of the tool carrier (not shown either) and at the same time during this operation is rotated about the axis of rotation A. As an alternative to this, the container 3 can obviously also be moved towards the closing head 4 and where applicable rotated. As a result of this, the spring element or the helical spring 5 is compressed and exerts a mounting force onto the accommodating head 4 a and as a result onto the closure 1 and consequently the container opening 2 and the container 3. For the force from outside or the external force F_(A) results in the accommodating cup 4 a dipping increasingly into the guide cylinder 4 c of the base 4 b along the displacement path or stroke H.

At the same time as the space between the accommodating cup 4 a and the base 4 b is reduced along the path of displacement H, the two magnets or permanent magnets 6, 7 of the internal force-supporting element 6, 7 move closer to each other. As a result of this, the inner force F_(I) also exerted by said magnets onto the spring element 5 mounts. This is indicated in FIG. 2 by the corresponding force curve of the force F or of the inner force F_(I) and the external force F_(A) over the path s along the stroke H.

As a result of the mounting inner force F_(I), the force F_(A) working from outside onto the closing head 4 a along the displacement path s or along the stroke H can be increasingly reduced according to the invention, as is indicated by the course of the force F_(A) in FIG. 2. Nevertheless, as a result, the spring element 5 is acted upon by a compound force F_(A)+F_(I), which approximately describes the force development shown by the broken line and consequently corresponds to the force curve that was applied previously in the prior art purely by the force from outside F_(A). 

1. An apparatus for closing containers with a closure, said apparatus comprising: at least one closing head that, for applying the closure, is displaced in a direction of a container opening along a displacement path by a predetermined force applied from outside, wherein the closing head includes an internal force-supporting element that generates an inner force that supports the force applied from outside.
 2. The apparatus of claim 1, wherein the force-supporting element is configured to develop an inner force that mounts as the closing head is displaced along the displacement path in the direction of the container opening.
 3. The apparatus of claim 1, wherein the inner force and the external force cooperate to compress at least one spring element.
 4. The apparatus of claim 3, wherein the spring element is supported at one end on an accommodating cup for the closure and supported at another end on a base, wherein the accommodating cup dips into a guide cylinder of the base, thus defining the displacement path.
 5. The apparatus of claim 4, wherein the force-supporting element is located parallel to the spring element.
 6. The apparatus of claim 4, wherein the spring element surrounds the force-supporting element.
 7. The apparatus of claim 1, wherein the closing head comprises an accommodating cup for supporting a closure, and a base, wherein the force-supporting element is connected at one end to the accommodating cup and at another end to the base.
 8. The apparatus of claim 1, wherein the force-supporting element is realized as comprises two magnets.
 9. The apparatus of claim 8, wherein the two magnets lie opposite each other such that poles of opposite polarity face each other.
 10. The apparatus of claim 1, wherein the closing head is rotationally symmetric about an axis of rotation.
 11. A method for closing a container with a closure, said method comprising: displacing a closing head supporting a closure in a direction of a container opening of the container along a displacement path by acting upon said closing head with a predetermined force from outside, said displacement of said closing head resulting in generation of an inner force inside the closing head by a force-supporting element, said inner force supporting the force applied from outside.
 12. The method of claim 11, further comprising compressing a spring element by causing the inner force and the external force to act on the spring element substantially in the same direction for the compression thereof.
 13. The method of claim 12, wherein the spring element acts, in the direction of a container opening, upon an accommodating cup that supports the closure.
 14. The method of claim 11, wherein the inner force (FI) mounts as the closing head is displaced along the displacement path in the direction of the container opening.
 15. The method of claim 11, wherein the closure is a screw-type closure, the method further comprising rotating the closing head about an axis of rotation to screw-connect the screw-type closure onto the container.
 16. The method of claim 14, wherein the inner force mounts exponentially.
 17. An apparatus for closing a container with a closure, said apparatus comprising: a closing head for supporting the closure, said closing head being configured to be displaced toward the container by an external force; and means for generating an internal force in response to said displacement, said inner force being acted in a direction that cooperates with the external force.
 18. The apparatus of claim 17, where said means for generating an internal force comprises means for generating a mounting that increases with displacement of said closing head toward said container by said external force.
 19. The apparatus of claim 17, wherein said means for generating an internal force comprises means for generating a magnetic force. 